1. Field of the Invention
The present invention relates to rearview mirrors for vehicles, and more particularly to a system for improved focusing of a rearview mirror including repositioning a rearview mirror automatically in response to a vehicle directional signal.
2. Description of the Prior Art
Rearview mirrors are commonly used on vehicles to expand the driver's field of vision. The driver can better observe traffic conditions behind the vehicle with a consequent improvement in traffic safety. A conventional rearview mirror system of the type used on passenger cars is shown in FIG. 1 as used in a typical modern three-lane highway. The three lanes are identified with the numerals 1, 2, and 3. Each lane is defined by highway markers 5, 7, where solid lines 5 typically denote the path of travel in a single direction as shown by the arrow, and the spaced lines 7 separate the individual lanes within a given direction of travel. Six vehicles A, B, C, D, E, and F are shown in various positions in the respective lanes. A conventional rearview mirror system installed on vehicle A includes a mirror 10 on the left side of the vehicle, a mirror 12 on the right side of the vehicle, and a mirror 13 and mounted and generally centered within a front portion of the passenger compartment. The mirrors 10, 12 are typically focused to provide a view of objects in the traffic lanes immediately to the left and right, 1 and 3, respectively, and to the rear of vehicle A. Thus a field of view subtended by angle .alpha. may be seen in the left-hand mirror 10 from a typical driver's position within vehicle A, and a rear field of view subtended by angle .beta. may be seen in right-hand mirror 12. The mirror 13 is typically focused to provide a view of objects immediately behind the vehicle, with a field of view subtended by angle .GAMMA.. Thus, a driver sitting in vehicle A can readily observe the presence and movements of vehicles D, E, and F without shifting the eyes too far out of the line of travel of vehicle A.
However, vehicles B and C are typically not within the driver's field of vision in any of the rearview mirrors 10, 12 or 13. Being slightly behind vehicle A in the direction of travel, vehicles B and C are similarly outside the peripheral vision of the driver in vehicle A. Thus, vehicles B and C are located in positions customarily referred to as the "blind spot", and cannot be seen by a driver in vehicle A unless the driver were to direct the line of vision away from the direction of travel to look either to the left or to the right. Thus, if a driver in vehicle A seeks to move vehicle A to either lanes 1 or 3, the driver must remove his eyes from the road and look to the right or left before changing direction.
To overcome the problem of the "blind spot", it is known to use a variety of convex mirrors either in place of or in addition to rearview mirrors 10, 12. Such mirrors are available with various radii of curvature ranging from about 8 inches to 24 inches which optically expand the field of vision subtended by angles .alpha. and .beta.. However, the images projected by convex mirrors are badly distorted, which make it difficult to identify objects and accurately determine the approximate distance to an object being observed.
Further, drivers frequently do not adjust the mirrors 10, 12, and 13 to obtain the proper focus and thus maintain the optimum field of vision for safety. It is desirable therefore to provide a means whereby a driver can quickly and properly focus a rearview mirror to an optimum position.
It is further desirable to provide a means whereby a driver, upon signaling a change in lane of the vehicle, can readily check the blind spot without distortion and without shifting the field of vision too far out of the line of travel of the vehicle in order to ensure a safe change of lane.